'\" t
.\"     Title: kcapi_cipher_stream_op
.\"    Author: 
.\" Generator: DocBook XSL Stylesheets vsnapshot <http://docbook.sf.net/>
.\"      Date: April 2024
.\"    Manual: Programming Interface
.\"    Source: libkcapi Manual 1.4.0
.\"  Language: English
.\"
.TH "KCAPI_CIPHER_STREAM_" "3" "April 2024" "libkcapi Manual 1\&.4\&.0" "Programming Interface"
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.SH "NAME"
kcapi_cipher_stream_op \- obtain processed data (stream)
.SH "SYNOPSIS"
.HP \w'ssize_t\ kcapi_cipher_stream_op('u
.BI "ssize_t kcapi_cipher_stream_op(struct\ kcapi_handle\ *\ " "handle" ", struct\ iovec\ *\ " "iov" ", size_t\ " "iovlen" ");"
.SH "ARGUMENTS"
.PP
\fIhandle\fR
.RS 4
[in] cipher handle
.RE
.PP
\fIiov\fR
.RS 4
[out] scatter/gather list pointing to buffers to be filled with the resulting data from a cipher operation\&.
.RE
.PP
\fIiovlen\fR
.RS 4
[in] number of scatter/gather list elements\&.
.RE
.SH "DESCRIPTION"
.PP
This call can be called interleaved with
\fBkcapi_cipher_stream_update\fR
to fetch the processed data\&.
.PP
This function may cause the caller to sleep if the kernel buffer holding the data is empty\&. The process will be woken up once more data is sent by calling
\fBkcapi_cipher_stream_update\fR\&.
.PP
Note, when supplying buffers that are not multiple of block size, the buffers will only be filled up to the maximum number of full block sizes that fit into the buffer\&.
.PP
The kernel supports multithreaded applications where one or more threads send data via the
\fBkcapi_cipher_stream_update\fR
function and another thread collects the processed data via kcapi_cipher_stream_op\&. The kernel, however, will return data via
\fBkcapi_cipher_stream_op\fR
as soon as it has some data available\&. For example, one thread sends 1000 bytes to be encrypted and another thread already waits for the ciphertext\&. The kernel may send only, say, 500 bytes back to the waiting process during one
\fBkcapi_cipher_stream_op\fR
call\&. In a subsequent calls to
\fBkcapi_cipher_stream_op\fR
more ciphertext is returned\&. This implies that when the receiving thread shall collect all data there is,
\fBkcapi_cipher_stream_op\fR
must be called in a loop until all data is received\&.
.PP
\fIreturn\fR
number of bytes obtained from the kernel upon success; a negative errno\-style error code if an error occurred
.SH "AUTHOR"
.PP
\fBStephan Mueller\fR <\&smueller@chronox.de\&>
.RS 4
Author.
.RE
.SH "COPYRIGHT"
.br